Wales received a massive influx of English migrant workers to work in the mines in the valleys,in the 19thC adding to the general anglicisatiin of the most populated South. So their Welsh identity is paper thin and many identify more as British. It's also home of the most deprived areas in the 'UK' (due to Thatcher's deindustrialisation) which are a breeding ground for those who can't go beyond scapegoating immigrants for all their problems.